From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753659Ab3IYQS3 (ORCPT ); Wed, 25 Sep 2013 12:18:29 -0400 Received: from mail-wg0-f46.google.com ([74.125.82.46]:36699 "EHLO mail-wg0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751072Ab3IYQS1 (ORCPT ); Wed, 25 Sep 2013 12:18:27 -0400 From: Frederic Weisbecker To: LKML Cc: Frederic Weisbecker , Benjamin Herrenschmidt , Paul Mackerras , Ingo Molnar , Thomas Gleixner , Peter Zijlstra , "H. Peter Anvin" , Linus Torvalds , James Hogan , "James E.J. Bottomley" , Helge Deller , Martin Schwidefsky , Heiko Carstens , "David S. Miller" , Andrew Morton Subject: [PATCH 5/7] irq: Justify the various softirq stack choices Date: Wed, 25 Sep 2013 18:18:04 +0200 Message-Id: <1380125886-10341-6-git-send-email-fweisbec@gmail.com> X-Mailer: git-send-email 1.8.3.1 In-Reply-To: <1380125886-10341-1-git-send-email-fweisbec@gmail.com> References: <1380125886-10341-1-git-send-email-fweisbec@gmail.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org For clarity, comment the various stack choices for softirqs processing, whether we execute them from ksoftirqd or local_irq_enable() calls. Their use on irq_exit() is already commented. Signed-off-by: Frederic Weisbecker Cc: Benjamin Herrenschmidt Cc: Paul Mackerras Cc: Ingo Molnar Cc: Thomas Gleixner Cc: Peter Zijlstra Cc: H. Peter Anvin Cc: Linus Torvalds Cc: Paul Mackerras Cc: James Hogan Cc: James E.J. Bottomley Cc: Helge Deller Cc: Martin Schwidefsky Cc: Heiko Carstens Cc: David S. Miller Cc: Andrew Morton --- kernel/softirq.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) diff --git a/kernel/softirq.c b/kernel/softirq.c index 9f8092b..2b4328e 100644 --- a/kernel/softirq.c +++ b/kernel/softirq.c @@ -170,8 +170,13 @@ static inline void _local_bh_enable_ip(unsigned long ip) */ sub_preempt_count(SOFTIRQ_DISABLE_OFFSET - 1); - if (unlikely(!in_interrupt() && local_softirq_pending())) + if (unlikely(!in_interrupt() && local_softirq_pending())) { + /* + * Run softirq if any pending. And do it in its own stack + * as we may be calling this deep in a task call stack already. + */ do_softirq(); + } dec_preempt_count(); #ifdef CONFIG_TRACE_IRQFLAGS @@ -769,6 +774,10 @@ static void run_ksoftirqd(unsigned int cpu) { local_irq_disable(); if (local_softirq_pending()) { + /* + * We can safely run softirq on inline stack, as we are not deep + * in the task stack here. + */ __do_softirq(); rcu_note_context_switch(cpu); local_irq_enable(); -- 1.8.3.1